US3055453A - Collapsible trestle - Google Patents

Description

Sept. 25, 1962 A. B. VANYO COLLAPSIBLE TRESTLE Filed May 10, 1961 INVENTOR Andrew 6. l/anyo nite rates Patet 3,055,453 COLLAPSEBLE TRESTLE Andrew B. Vanyo, 415 Myer St., Duryea, Pa. Filed May 10, 1961, Ser. No. 109,198 1 Claim. (Cl. 182-186) My invention relates to supports, and more particularly, to a collapsible plank horse or trestle adapted for use in forming scaffolding and the like.

In my Patent No. 2,938,596, issued May 31, 1960, for Collapsible Trestles, there is described and claimed a trestle structure specifically designed to accommodate planks or similar structural elements of random widths, whereby planks of different widths, usually available at a building site, may be used with the trestle, thus eliminating transport of planks of fixed width. In accordance with the preferred embodiment of the invention described in the aforementioned patent, the trestle is provided with leg adjusting means, whereby the width of the plank receiving opening may be gradually varied over a comparatively wide range, with simultaneous proportional variation of the distance between the supporting ends of the legs; there is also described a modified form of the plank horse wherein the width of the plank receiving opening is varied by flexing the upper cross-brace, comprising a leaf spring secured between the upper portions of the legs of said plank horse.

While both forms of the above referred to trestles have had wide acceptance by carpenters, painters, plasterers, and other engaged in building construction generally, and more particularly building construction of the nature that suitable planks or other supports are available at the site, there has recently been a demand for plank horses or trestles designed for use with planks of fixed width only, to serve as adjuncts or supplements to trestles adapted to accommodate planks of random widths. With reference to the need for trestles adapted for use with planks of fixed width, it has been found by various building crafts using this type of scaffolding, that it is desirable to have plank horses and a plank as a unit, for the reason that during certain phases of the construction work planks or other support members, suitable for use with the trestles, are not available at the building site. Additionally, the provision of a scaffolding unit, that is to say, trestles and associated plank, is advantageous in connection with work incident to the modernization of homes and other buildmgs.

An object of my invention is to provide an improved plank horse or trestle.

Another object of my invention is to provide a collapsible trestle for use in forming scaffolding, wherein a plank or other structural member is securely clamped in horizontal supporting position between the upper ends of the legs of the trestle.

Yet another object of my invention is to provide a collapsible trestle having improved plank supporting means adapted to retain the plank in horizontal operative position between the upper free ends of the legs of the trestle.

Still another object of my invention is to provide a collapsible trestle having improved plank clamping and supporting means constructed and arranged whereby to prevent relative movement between the plank and the trestle, when the plank is in the operative position between the upper free ends of the trestle.

A further object of my invention is to provide an improved collapsible plank horse, or trestle, having means to prevent accidental collapse of trestle during use thereof. With these and other objects in view, which may be incident to my improvements, the invention consists in the parts and combinations to be hereinafter set forth and claimed, with the understanding that the several necessary elements comprising my invention, may be varied in construction, proportions and arrangements, without departing from the spirit and scope of the appended claim.

In order to make my invention more clearly understood, I have shown in the accompanying drawings means for carrying the same into practical efiect, without limiting the improvements in their useful application to the particular constructions which, for the purpose of explanation, have been made the subject of illustration.

In the drawings:

FIGURE 1 is a perspective view of a collapsible plank horse of the present invention, showing a plank or other structural member in operative position thereon;

FIG. 2 is a front elevational view, partly in section, of one of the plank horses shown in FIG. 1, with the plank removed;

FIG. 3 is a fragmentary view taken along line 33 of FIG. 1; and

FIG. 4 is a fragmentary, detailed view of one of the plank supporting members.

Referring to the drawings, my improved collapsible trestle or plank horse comprises leg members designated generally by numerals 1 and 2, formed from a structurally strong, lightweight meal or metal alloy, each of the legs being of U-shape in cross section having a flat rectangular shaped bottom portion 3, and similarly shaped side flanges 4. As will be seen in FIGS. 2-4, the upper portions of the legs 1 and 2 are conformed to receive plank supporting members 5 and 6, respectively, and the lower portion of each leg is angularly disposed with respect to the top portion, as shown in FIGS. 1 and 2, the legs being connected by means of a bottom brace 7, and a top brace 8.

The bottom brace comprises a channel-shaped arm 9 pivotally attached as at Ill to the side flanges 4 of the leg 2, and overlapping a portion of a similarly shaped arm 11, pivotally attached as at 12 to the flanges 4 of the other leg 1, the arms being connected by means of a pivot pin 13. In order to prevent accidental collapse of the trestle during use, the channel-shaped arm 9 is upwardly bent or olfset as at 14 in the vicinity of its overlapping portion, whereby to provide an over-center lock joint when the arms 9 and 11 are in abutting overlapped position. The upper arm 9 is formed with a hook 15 for raising the arm to break the joint, when it is desired to collapse the legs, and for moving the arm into overlapping position with respect to the arm 11 when it is desired to place the legs in the operative, expanded position. The top brace 8 comprises a channel-shaped arm 16 pivotally attached at one end to the side flanges 4 of the leg 2 by means of a pin 17, and rigidly secured at its opposite end to the side flanges 4 of leg 1 by means of welding or bonding, as indicated at 18.

The plank supporting member 5 is comprised of a side flange 19 and a bottom flange 20, perpendicular thereto, the side flange being formed with integrally spaced prongs or teeth 21 adapted to grip the face 22 of a plank 23. The plank supporting member 6 is comprised of a side 3 flange 24 and a bottom flange 25, which flange forms an obtuse angle with the side flange 24, the latter flange also being provided with integrally spaced prongs or teeth 21, adapted for gripping engagement with the face 26 of the plank.

With reference to the construction and arrangement of the plank supporting member 6, the purpose of forming the bottom flange 25 at an obtuse angle with respect to the side flange 24 is to enable the plank to be clamped in horizontal seated position, when the trestle leg 2 is moved outwardly to plank supporting position, as shown in full lines, FIG. 2. If each of the plank supporting members comprises a vertical flange and a horizontal flange, in other words having flanges arranged at right angles, it will be readily seen that when the pivoted leg 2 is moved to plank clamping position the lower inner edge of the horizontal flange would lie in a plane above the horizontal, thereby tilting the plank at an angle to the horizontal, with resultant faulty gripping of the plank face 26, (FIG. 3) by the prongs or teeth 21, which in turn tends to lift or force the lower plank edge away from the horizontal.

It will be noted that the above described improper seating of the plank obtains when two trestles are used with a plank, and the pivotal legs 2 are on the same side of the scaflord, for example, as shown in FIG. 1. If however, the pivotal legs are juxtaposed so as to bring the pivotal legs on opposite sides of the scaffold, it will be observed that the conditions, which obtain when the pivotal legs are on the same side of the scaffold, are aggravated for the reason that the plank is then free to tilt about its diagonally opposite points of support on the lower horizontal flanges.

In accordance with the present invention, the plank is supported in clamped, seated, horizontal position between the upper ends of the legs of the trestle in such fashion that it is prevented from tilting or wobbling, irrespective of the location of the pivotal legs with respect to the scaffold, that is, regardless of Whether the pivotal legs are positioned on the same side or on opposite sides of the scaffold. This is an important feature of my invention and is accomplished by means of the angulation of the lower flange 25 of the plank support member 6 with respect to the vertical flange 24 of this support member.

Reference being had to FIGS. 2 and 3, it will be noted that the angle between flanges 24 and 25 is slightly greater than 90 due to the fact that flange 25 is bent downwardly, and accordingly it is out of alignment with the horizontal plane of the bottom surface 28 of the plank when the plank is in the seated, clamped position, shown in FIG. 3. As will be seen in FIG. 2 by reason of the downward inclination of the flange 25 it will assume a substantially horizontal position when the pivotal leg 2 is in the dotted line position of FIG. 2, so that the plank 23 may be readily inserted between the flanges 19 and 24-without interference with the prongs 21, and rest upon the substantially coplanar flanges 20 and 25. As the pivotal leg 2 begins to move to clamping position, full lines FIG. 2, the lower edge 29 of the plank slides along the upper surface 25' of the flange 25 (FIG. 3) and finally abuts the line of intersection between the planes 24 and 25, when the prongs 21 are fully embedded in the face 26 of the plank. Movement of the lower edge 29 of the plank into abutting supported position on the flange 25 is effected without raising the plank out of the horizontal position it assumed when initially placed on the flanges 20 and 25, thus permitting accurate positioning of the plank on the support members, and its subsequent positive clamping in desired horizontal position.

In connection with the arrangement of the plank supporting members and 6, with respect to the legs 1 and 2 of the trestle, it will be noted that the side flanges 19 and 24 of the support members 5 and 6, respectively, are reinforced against possible bending or outward movement relative to their respective bottom flanges 20 and 25, by means of plates 27, which are coextensive with the side 4 flanges and secured thereto and to the upper portions of the bottom flanges of the legs.

In forming a scaffolding it will be understood that at least two trestles are used to support the plank in the vicinity of the ends thereof; however, additional trestles may be positioned intermediate of the plank ends, if desired. To assemble the scaffolding, assuming that the leg 2 of one of the trestles is in the collapsed position, as shown in dottedlines in FIG. 2, the plank 23 is placed on the support members 5 and 6, with the side faces 22 and 26 of the plank abutting the prongs 21, and the bottom face 28 of the plank resting on portions of the bottom flanges 20 and 25 of supports 5 and 6, respectively. The lower portion of leg 2 is then pulled or otherwise moved outwardly about its pivot point 17, thus causing the flange 25 to move inwardly beneath the plank, with the prongs 21 of the flanges 19 and 24 penetrating the side faces 22 and 26 respectively. After initial penetration of the prongs with the side faces of the plank, the pivotal arm 9 of the lower brace 7 is pushed downwardly into the overlapping relationship with the arm 11, thereby forcing the prongs into the sides of the plank. During the abovedescribed movement of the support members the lower bottom edge 29 of the plank slides along the upper surface 25' of the flange 25, and when the arm 9 reaches its seated, overlapping position, the edge 29 is wedged into the corner formed between the flanges 24 and 25, and since the pivotal leg 2 is maintained in extended position by means of the over-center lock joint of the arms 9 and 11, the plank is restrained against movement with respect to the flange 25. The second trestle may then be secured to the opposite end portion of the plank in like fashion. It will be appreciated that if assistance is available, the trestles may be secured to a plank simultaneously.

While the use of only two trestles has been described it will be understood that additional trestles may be used to provide adequate support for a plank. It will also be understood that the dimensions of the trestles may be varied to suit the conditions or environments under which the scaffolding is to be used, and if desired, the trestles may be equipped with rollers or wheels. It will be further understood that, although the bottom flange of only one of the plank supporting members is formed at an obtuse angle with respect to its adjacent flange, the present invention comprehends the formation of each bottom flange at an obtuse angle to its respective adjacent flange.

There has been described and illustrated a device capable of performing all of the specifically mentioned objects of this invention as well as others which are apparent to those skilled in the art. Various uses of the present invention may be made employing the described structure. Accordingly, it is apparent that variations as to operation, size and shape, and rearrangement of elements may be made without departing from the spirit of the invention. Accordingly, limitation is sought only in accordance with the scope of the following claim.

I claim:

A plank horse of the character described, comprising a pair of symmetrically shaped metallic leg members having upper and lower portions, each of said leg members comprising a rectangular shaped bottom flange and a pair of rectangular side flanges arranged at right angles to the plane of the bottom flange, the lower portion of each leg being angularly disposed with respect to the upper portion thereof, a first plank supporting member secured to the top of the upper portion of one of the legs, a second plank supporting member secured to the top of the upper portion of the other leg, each of said plank supporting members having a side flange and a bottom flange, a reinforcing plate coextensive with and secured to the side flange and to the upper portion of the respective leg, the side flange being provided with a plurality of spaced prongs adapted for engagement with an edge of a plank, the bottom flange of the first plank supporting member being perpendicular to its respective side flange, the bottom flange of the second plank supporting member forming an obtuse angle with its respective side flange, an arm having one end rigidly attached to the upper portion of the leg to which the first plank supporting member is secured, the opposite end of the arm being pivotally connected to the upper portion of the other leg, whereby said other leg may be pivoted about the arm to mount a plank in a clamped seated horizontal position between the first and second plank supporting members, and thereby prevent the plank from tilting or wobbling with respect to the plank horse, and a pair of pivotally connested, overlapping channel-shaped arms, the free ends of the arms being pivotally connected to the lower por- 6 tion of the respective legs, the overlapping arm being ofiset in the vicinity of its overlapped portion, thereby providing an over-center lock joint when the arms are in abutting, overlapping position for maintaining the legs 5 in expanded, operative position.

References Cited in the file of this patent UNITED STATES PATENTS 10 Re. 23,097 Imes Apr. 12, 1949 787,922 Hoxie Apr. 25, 1905 2,938,596 Vanyo May 31, 1960

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